“Though I had come to think of Knocknaree as though it had happened to another and unknown person, some part of me had been here all along […] I never left that wood.” 

Rob makes this statement early in the book, and it contradicts much of what he says later to deny the effect that the disappearance of his friends has on him.

“We are so used to things transmuting into whatever we would like them to be that it comes as a profound outrage to encounter death, stubbornly unspinnable, only and immutably itself.” 

Rob is offering an offhand comment about Mel’s reaction to death, yet he seems to be explaining his own profound reaction to the loss of his friends.

“I suppose the whole thing must have had its effects on me, but it would be impossible—and to my mind, pointless—to figure out exactly what they were.” 

Based on later events in the story, Rob’s comment indicates how out of touch he is with his own psyche. The loss of his friends had a profound and disturbing impact that he refuses to acknowledge here.